Supplementary Appendix 2. Characteristics of excluded studies.
Author, year	Reason for exclusion
Harrison & O’Moore, 1983	Crossover trial
Zreik et al., 1999	Crossover trial
Sayyah-Melli et al., 2012	Trigger was used in all arms
Masrour & Azad, 2018	Trigger was used in all arms
Thabet et al., 2024	Trigger was used in all arms